Effective freezing rate for semen cryopreservation in endangered Mediterranean brown trout (Salmo trutta macrostigma) inhabiting the Biferno river (South Italy)

This study was designed to determine: (i) the in vitro effects of different freezing rates on post-thaw semen quality of Mediterranean brown trout (Salmo trutta macrostigma) from the Biferno river; and (ii) the in vivo fertilization and hatching percentage of freezing rate giving rise to the best po...

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Bibliographic Details
Published in:Zygote (Cambridge) 2016-10, Vol.24 (5), p.668-675
Main Authors: Iaffaldano, Nicolaia, Di Iorio, Michele, Manchisi, Angelo, Esposito, Stefano, Gibertoni, Pier Paolo
Format: Article
Language:English
Subjects:
Animals
Cryopreservation - methods
Eggs
Endangered Species
Female
Fertilization in Vitro
Freezing
Hatching
Italy
Male
Nitrogen
Rivers
Salmo trutta
Salmo trutta macrostigma
Semen Analysis
Semen Preservation - methods
Sperm Motility
Spermatozoa - physiology
Thawing
Trout
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Summary:This study was designed to determine: (i) the in vitro effects of different freezing rates on post-thaw semen quality of Mediterranean brown trout (Salmo trutta macrostigma) from the Biferno river; and (ii) the in vivo fertilization and hatching percentage of freezing rate giving rise to the best post-thaw semen quality. Pooled semen samples were diluted 1:3 (v:v) in a freezing extender composed of 300 mM glucose, 10% egg yolk and 10% dimethyl sulfoxide (DMSO). The extended semen was packaged in 0.25 ml plastic straws and frozen at different heights above the liquid nitrogen surface (1, 5 or 10 cm) for 10 min to give three different freezing rates. Semen samples were thawed at 30°C for 10 s. The variables assessed after thawing were sperm motility, duration of motility and viability. Our results clearly indicate a significant effect of freezing rate on post-thaw semen quality. Semen frozen 5 cm above the liquid nitrogen surface showed the best quality after freezing/thawing. Based on these in vitro data, 2 groups of 200 eggs were fertilized with fresh semen or semen frozen 5 cm above the liquid nitrogen surface. Fertilization and hatching rates recorded for eggs fertilized with frozen semen were significantly lower (25.4% and 22.5%, respectively) than the ones obtained using fresh semen (87.8% and 75.5%, respectively). An effective freezing protocol will allow for the creation of a sperm cryobank to recover the original population of Mediterranean brown trout in the Biferno river.
ISSN:0967-1994
1469-8730
DOI:10.1017/S0967199415000647